This invention relates in general to machine components having an antifriction bearing between them for enabling one component to rotate relative to the other and, more particularly, to a rotary forming process and machine for uniting the machine components and the bearing.
Several basic arrangements exist by which the road wheels of automotive vehicles are attached to the suspension systems of such vehicles, and all involve a rotatable hub of one type or another. In one arrangement, the hub has a drive flange, and a spindle which projects from the flange. The spindle rotates in a housing on an antifriction bearing. The housing is bolted to the suspension system of the vehicle, while the road wheel is bolted to the flange of the hub. Thus, the hub and road wheel rotate relative to the housing and suspension system with minimum friction. The bearing has angular raceways which are oriented such that they take thrust loads in both axial directions as well as radial loads. Typically, the bearing has inner races mounted on the spindle and rolling elements arranged in two rows between raceways on the inner races and more raceways in the housing. A nut threads over the end of the spindle to retain the inner races on the spindle, and this has the effect of holding the entire arrangement together, that is, unitizing the hub assembly.
But the threads require an extra machining operation in the manufacture of the hub and the installation of the nut represents another assembly operation. These operations are reflected in the ultimate cost of the hub assembly. Furthermore, a nut may work loose and disrupt the setting of the bearing, perhaps causing wheel wobble and damaging the seals that isolate the interior of the bearing. and disrupt the setting of the bearing, perhaps causing wheel wobble and damaging the seals that isolate the interior of the bearing.
Others have employed a rotary-formed bead at the end of a hub spindle to hold a hub assembly together. But forming the bead, at least against the back face of the inner race for an antifriction bearing, requires precision and close monitoring of the forming operation to ensure that the forming operation does not distort the bearing and detract from its operation.
The present invention resides in a process for uniting two machine components and a bearing that is between the components for enabling one component to rotate relative to the other component. The bearing may have raceways that lie oblique to the axis of rotation and two rows of rolling elements, with the arrangement being such that the rolling elements transmit both radial and axial loads between the components. At least one of the raceways is on a race that is fitted to one of the machine components. Initially, that machine component projects beyond the race without obstructing the race, but thereafter the end of the component is radially and axially deformed in a rotary forming operation to produce a formed end which lies behind the race and unitizes the assembly. During the rotary forming operation, the component that is deformed rotates, relative to the other component, against a forming-tool. Preferably, the other component is restrained. The torque transferred from the rotating component to the stationary component may be monitored. For example, one of the components includes a flange which is held stationary such that the flange serves as a torque arm.
The present invention further provides a machine for uniting first and second machine components and a bearing that is between the components to enable one component to rotate relative to the other component about an axis of rotation, the bearing including raceways and rolling elements arranged in at least one row between the raceways, such that the rolling elements transmit radial and axial loads between the machine components, the bearing including a separate race that is fitted to the second component with the second component initially extending beyond a back face on the race in provision of an end portion, said machine comprising: a table that rotates about an axis and is configured to receive and engage the second machine component with that axis of the bearing and the axis of the table coincident, whereby the second component rotates with the table: a restraining member configured to engage the first machine component and prevent it from rotating with the second component: a head located axially beyond the table, but presented toward the table and having a spindle that rotates; and a forming tool carried by the spindle of the head and configured to radially and axially deform the end portion of the second component when the table and head are brought toward each other, with deformation causing the metal of the end portion to flow behind the back face of the separate race for the bearing, whereby the machine unites the first and second component and the bearings.
In a separate aspect the present invention provides a bearing unitized between two machine components manufactured in accordance with the above described process, wherein an end portion of one of the machining components is radially and axially deformed about the outer surface of one end of the bearing, a portion of the outer surface of the deformed end describing a substantially flat clamping surface.
In a further aspect the present invention provides a machine component for use in the above described process, the machine component having an end portion with a substantially flat inner surface and an outer surface formed from a plurality of tapered surfaces each at different angles to the axis of rotation of the component. Preferably, the outer surface of the end portion is described by three connecting tapered surfaces with the middle tapered surface being at a smaller angle to the axis of rotation than the outer two tapered surfaces.